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DUAL POWER PCMCIA CARD DESIGN

IP.com Disclosure Number: IPCOM000008344D
Original Publication Date: 1997-Sep-01
Included in the Prior Art Database: 2002-Jun-07
Document File: 5 page(s) / 246K

Publishing Venue

Motorola

Related People

R. W. Ady: AUTHOR [+2]

Abstract

PCMCIA cards have emerged as the defacto standard package for modular computer memory, modems, and other related devices. As a result, few laptop or notebook computers built today lack a PCMCIA port and most actually support multiple cards. The governing document for these cards-the PC Card Interface Standard--defines several physi- cal and electrical parameters required to insure compatibility between a wide range of cards and hosts. While the electrical interface requirements are the same for all cards, there are several allow- able physical designs referred to as Type 1, Type II, and Type 111. Each have different dimensions but utilize a common connector interface. As it turns out, two of the smaller Type II cards tit within the volume of a Type III slot, a fact which has lead many host device manufacturers to build "comhina- tion" PCMCIA ports which allow either a Type 111 card or two Type II cards to be used interchange- ably (with one of the Type II cards using the same connector receptacle occupied by the Type 111 card in the latter configuration). This design has likewise become the standard configuration for multiple PCMCIA port products, including most portable computers.

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MO7VROLA Technical Developments

8

DUAL POWER PCMCIA CARD DESIGN

by R. W. Ady, R.G. Uskali

BACKGROUND INFORMATION

  PCMCIA cards have emerged as the defacto standard package for modular computer memory, modems, and other related devices. As a result, few laptop or notebook computers built today lack a PCMCIA port and most actually support multiple cards. The governing document for these cards-the PC Card Interface Standard--defines several physi- cal and electrical parameters required to insure compatibility between a wide range of cards and hosts. While the electrical interface requirements are the same for all cards, there are several allow- able physical designs referred to as Type 1, Type II, and Type 111. Each have different dimensions but utilize a common connector interface. As it turns out, two of the smaller Type II cards tit within the volume of a Type III slot, a fact which has lead many host device manufacturers to build "comhina- tion" PCMCIA ports which allow either a Type 111 card or two Type II cards to be used interchange- ably (with one of the Type II cards using the same connector receptacle occupied by the Type 111 card in the latter configuration). This design has likewise become the standard configuration for multiple PCMCIA port products, including most portable computers.

  The PCMCIA electrical interface was also designed to be adaptable to many different applications but is limited in one significant regard: operating currents through the host-to-card interconnection must be held to one ampere or less. This excludes certain higher power applications from being built onto these cards without an auxiliary power system. As a result, PCMCIA cards requiring more current (such as wireless modems) typically include either auxiliary battery packs or-in more extreme cases-DC power jacks to provide the "boost" current from an adapter

plugged into the wall outlet.

PROBLEM DESCRIPTION

  Due to the relatively large size of battery cells and the limited selection of package styles, the battery supply invariably must reside outside the PCMCIA slot. This creates a protrusion vulnerable to damage which also may interfere with the operation of other features and/or accessories of the host device.

  Another issue with an auxiliary battery power source is the need to replace or recharge the cells. Replacing cells has the obvious environmental and convenience consequences. There are also problems with a rechargeable battery system: (1) if the battery is charged through the host device then the PCMCIA device will likely be duty-cycle-limited; that is, the unit must only be on a fraction of the time or there will not be sufftcient excess current to recharge the cells and thus they will eventually lose all their energy, or (2) if the battery is not charged through the host, then the user is required to carry extra cells or a special battery charger set-up in addition to that required for his or her host device, which results in a clumsy...